Endoscopy refers to looking inside the human body for medical reasons. Endoscopy may be performed using an instrument called an endoscope. Endoscopy is a minimally invasive diagnostic medical procedure used to evaluate the interior surfaces of an organ by inserting a small tube into the body, often, but not necessarily, through a natural body opening or through a relatively small incision. Through the endoscope, an operator may observe surface conditions of the organs, including abnormal or diseased tissue such as lesions and other surface conditions. The endoscope may have a rigid or a flexible tube and, in addition to providing an image for visual inspection and photography, the endoscope may be adapted and configured for taking biopsies, retrieving foreign objects, and introducing medical instruments to a tissue treatment region referred to as the work site. Endoscopy is a vehicle for minimally invasive surgery.
Laparoscopic surgery is a minimally invasive surgical technique in which operations are performed through small incisions (usually 0.5-1.5 cm), keyholes, as compared to larger incisions needed in traditional open-type surgical procedures. Laparoscopic surgery includes operations within the abdominal or pelvic cavities, whereas keyhole surgery performed on the thoracic or chest cavity is called thoracoscopic surgery. Laparoscopic and thoracoscopic surgery belong to the broader field of endoscopy.
A key element in laparoscopic surgery is the use of a laparoscope: a telescopic rod lens system that is usually connected to a video camera (single-chip or three-chip). Also attached is a fiber-optic cable system connected to a “cold” light source (halogen or xenon) to illuminate the operative field, inserted through a 5 mm or 10 mm cannula to view the operative field. The abdomen is usually insufflated with carbon dioxide gas to create a working and viewing space. The abdomen is essentially blown up like a balloon (insufflated), elevating the abdominal wall above the internal organs like a dome. Carbon dioxide gas is used because it is common to the human body and can be removed by the respiratory system if it is absorbed through tissue.
Minimally invasive therapeutic procedures to treat diseased tissue by introducing medical instruments to a tissue treatment region through a natural opening of the patient are known as Natural Orifice Translumenal Endoscopic Surgery (NOTES)™. In general, there are a variety of systems for inserting an endoscope through a natural opening in the human body, dissecting a lumen, and then, treating the inside of the abdominal cavity. For example, in U.S. Pat. No. 5,297,536, which is incorporated by reference herein, a sample treatment system is disclosed. This system is comprised of a dissecting device for perforating a lumen wall; an endoscope insert member for inserting an endoscope, a tube, an endoscope, and a pneumoperitoneum device for deflating the abdominal cavity; and a closing device.
When transluminal endoscopic surgery is carried out using this system, an endoscope insert member and overtube are first inserted through a natural opening in the human body (mouth, anus, or vagina, for example). The overtube may be absorbed to a required organ wall by vacuum pressure, thus being fixed thereon. An incising instrument may be passed through the overtube, or through the working channel of the endoscope, to form a perforation through the surface of the organ wall. An inflation device, such as a balloon, may be placed in the incision and inflated to radially expand the incision. Once the incision has been enlarged, the overtube then may be inserted through the organ wall to serve as a working channel for the endoscope and other tools. After surgery of the inside of the abdominal cavity is complete, the overtube may be removed from the enlarged incision, the perforation in the organ wall may be closed by an O-ring, and the endoscope and overtube may be withdrawn from the body.
In various known techniques, difficulties may arise when inserting the overtube through the organ wall or other tissue. For example, the organ wall may catch or snag at the interface between the distal end of the tube and the inflation device. Such interference with the organ wall may impede the smooth entry of the overtube through the organ wall. Accordingly, in the field of endoscopy, there remains a need for improved methods and devices for inserting an overtube through a tissue wall during an endoscopic surgical procedure.